Quote: Turning to campaign medals, there were just the 3 in WW1.
I beg to differ, if Campaign is taken as a subset of War, as in "Burma", Africa" etc.
The 1914 star was, and the 1914-15 star was at a pinch, a campaign medal, although the latter was awarded to RN [for example] out of the F&F area.
The British War Medal was just that: not a campaign in any sense that I infer above ........... all theatres, all periods.
The Victory medal was specifically to commemorate the Victory, a victory in war, not a campaign.
And the Mercantile Marine medal could be earned any time, anywhere, for a single voyage in a danger zone.
So I make that one, or just possibly two Campaign medals.
The maximum wearable was four, if [unlikely but not impossible ...... I know of no cases but you can bet they existed!] a 1914 or 1915 soldier or RM was discharged and then went to sea.